K40 Type Laser Introduction


I've enjoyed woodworking for most of my life.  It usually involves noisy equipment, and makes a huge mess.  Also, the accuracy depends on the materials used, the tools, the setup, the jig, the user's skill, and most importantly, luck.  Once the human element is mostly removed, the quality of the work greatly increases!

The very common K40 type laser is very popular, for good reason.  As they come, they are lacking basic safety features, and have a limited work area. With some simple mods, this thing can be a workhorse.  You could buy a Glow Forge, which is a nice, ready to use package.  But it has some major downsides.  It's very expensive.  The software is proprietary, and is web based.  If the network is down, or they go out of business, you might have a paperweight.  There are also no options for upgrades, such as a larger/more powerful laser tube, or a rotisserie for engraving cups/mugs.

K40 lasers start around $400 on eBay, but lack a warranty, and require more tinkering to get started.  I bought an Omtech brand from Amazon.  It came almost ready to run.  The laser had been tested, the mirrors aligned, LED lighting inside the box, and a laser pointer to show where the cut will be made.  The actual laser beam is invisible

It does need some mods, and I recommend adding a few optional ones.  I'll cover those below.


The box arrived fairly well packaged.

Until I made a more permanent workspace, I decided to use it on top of a Harbor Freight roll around tool box.  The rolled edge on top of the box was slick painted metal.  I used some edge trim to prevent the laser from sliding around.

This material has a rubber type texture, and a metal clip inside.  I used heavy diagonal pliers to cut it to length.
This worked great.  The entire thing can be quickly moved in my garage.
The included water pump, to cool the laser during operation, is sitting behind the laser enclosure.

The 40 Watt tube is the width of the enclosure.  If you later wish to bump the tube power up to 50W-80W, simply buy the tube online, buy a larger power supply, and add an extension to the end of the enclosure.  There's already a removable plate on the side of the enclosure to accommodate this.
The stock work area is rather small.  The aluminum plate, and blue colored plate around the work area, are quickly removed with a few screws.
I made a new work platform from a piece of scrap aluminum.  The "punk" spikes were purchased in bulk on Amazon.  They hold up the material being cut, to allow airflow underneath.  This makes for a cleaner cut, and less likely to create a fire.
I used a lab jack under the new work platform.  It has a nob that can be turned to adjust the height of the platform.  The laser lens is a fixed focal length.  This requires the material to be the correct height from the laser.  The lab jack makes this a very quick and easy task.  If you're always using 3mm work or acrylic, the jack never needs to be adjusted after the initial setup.
Not required, but highly recommended, a current meter.  You can mount it on the outside of the case, but I put mine inside the enclosure next to the power supply. The netlore suggestion is to keep the current below 10 mA to ensure the tube lives a long life.  Higher current equals a shorter lifespan.
There are some very good videos of how to do a "Ramp Test" to determine the correct work height.  Afterwards, you can do a power test to determine what the settings on the laser actual mean. 
At 9mA, the laser cuts 3mm (1/8") Baltic Birch plywood like butter.  It cuts 3mm acrylic panels just as cleanly.
Digging through my electronic junque pile, I found a connector that fits the jack on the power supply.  This is where to connect door switches to cut the laser power.

The files for the 3D printed switch mounts are available for free on ThingiVerse.  I used 3M VHB tape to adhere the mounts to the case.
A simple lever switch provides a safety cut-off each time the door is opened.  The reason this is NEEDED is the laser is invisible.  If you reach inside the box while it's cutting, you can easily get a hand in front of the beam between the mirrors.  You can get a significant burn at the least.  If the beam reflects from a watch face, or ring, you could lose an eye.
The switch for the laser cutting area on the left, another switch for the power supply area on the right.  Note the push blocks on the lids above that press the switches when the doors are closed.
The stock exhaust fan works "ok".  The air plenum inside overhangs the work area.  Dumb design.
I cut it back using an angle grinder.  This gives full use of the available cutting area. Actual available cutting area is now 325mm x 219.96mm, or 12.79" x 8.65". Works much better now.  I may still remove the plenum completely later.  Not sure that it's even needed. 
These are a few of things I made initially.  The National Park sign is 3D, which really makes it nice.  The design is a freebie on ThingiVerse.
This is a simple drink coaster I made and sold on Etsy.
I made a bunch of these, and some boxes for mini bottles of Fireball Whiskey.  They were great stocking stuffers for my extended family.
The design has no hardware.  Just laser cut pieces, glued together.  Has a wooden hinge point.
I bought a nice roll around tool box that doubles as a work table.
The drawers are great, but it doesn't come with dividers.  I laser cut some boxes, and some holders for Dremel moto-tool bits.
I made a batch of heart shaped boxes for Valentine's Day.  Sold these on eBay and Etsy.  The curved section has many tiny slits, creating a "living hinge".  The plywood easily bends to curved shapes with the many tiny cuts.

I will be making a lot more projects from acrylic.  This stuff engraves and cuts beautifully.  I experimented on a single piece until I had the setting dialed in.  The puck base was part of a kit, that included one piece of acrylic.  They want you to buy more of their pre-cut pieces of clear acrylic.  But it is EASY to cut your own from a 12"x12" sheet.  The base has LEDs inside that change colors.  Comes with a remote.  Looks a lot better in person.  The kit is linked below.

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Last updated 03/07/22    All rights reserved.